In my Deep Space Carrier series, I have to stop off to mine tritium quite a lot, but tritium is simply an isotope of hydrogen, and should be easily convertible via the fusion powerplants on the carrier. Add a tritium processing module that scoops hydrogen off the nearby star and converts it to tritium. I would say the tritium market would be affected, but the prevailing wisdom I've seen from the mining community is you don't mine tritium...you go mine platinum and then just buy tritium with the profits, so not sure that's much of an issue.